V$SQL_WORKAREA

V$SQL_WORKAREA displays information about work areas used by SQL cursors. Each SQL statement stored in the shared pool has one or more child cursors that are listed in the V$SQL view. V$SQL_WORKAREA lists all work areas needed by these child cursors; V$SQL_WORKAREA can be joined with V$SQLAREA on (ADDRESS, HASH_VALUE) and with V$SQL on (ADDRESS, HASH_VALUE, CHILD_NUMBER).

You can use this view to find out answers to the following questions:

What are the top 10 work areas that require the most cache area?

For work areas allocated in AUTO mode, what percentage of work areas are running using maximum memory?

Column

Datatype

Description

ADDRESS

RAW(4 | 8)

Address of the parent cursor handle

HASH_VALUE

NUMBER

Hash value of the parent statement in the library cache. Two columns PARENT_HANDLE and HASH_VALUE can be used to join with V$SQLAREA to locate the parent cursor.

CHILD_NUMBER

NUMBER

Number of the child cursor that uses this work area. The columns PARENT_HANDLE, HASH_VALUE, and CHILD_NUMBER can be used to join with V$SQL to locate the child cursor using this area.

WORKAREA_ADDRESS

RAW(4 | 8)

Address of the workarea handle. This is the "primary key" for the view.

OPERATION_TYPE

VARCHAR2(20)

Type of operation using the work area (SORT, HASH JOIN, GROUP BY, BUFFERING, BITMAP MERGE, or BITMAP CREATE)

OPERATION_ID

NUMBER

A unique number used to identify the operation in the execution plan. This identifier can be joined to V$SQL_PLAN to locate the operation that uses this work area.

POLICY

VARCHAR2(10)

Sizing policy for this work area (MANUAL or AUTO)

ESTIMATED_OPTIMAL_SIZE

NUMBER

Estimated size (in KB) required by this work area to execute the operation completely in memory (optimal execution). Derived from either optimizer statistics or previous executions.

ESTIMATED_ONEPASS_SIZE

NUMBER

Estimated size (in KB) required by this work area to execute the operation in a single pass. Derived from either optimizer statistics or previous executions.

LAST_MEMORY_USED

NUMBER

Memory (in KB) used by this work area during the last execution of the cursor

LAST_EXECUTION

VARCHAR2(10)

Indicates whether this work area runs using OPTIMAL, ONE PASS, or ONE PASS memory requirement (or MULTI-PASS), during the last execution of the cursor

LAST_DEGREE

NUMBER

Degree of parallelism used during the last execution of this operation

TOTAL_EXECUTIONS

NUMBER

Number of times this work area was active

OPTIMAL_EXECUTIONS

NUMBER

Number of times this work area ran in optimal mode

ONEPASS_EXECUTIONS

NUMBER

Number of times this work area ran in one-pass mode

MULTIPASSES_EXECUTIONS

NUMBER

Number of times this work area ran below the one-pass memory requirement

ACTIVE_TIME

NUMBER

Average time this work area is active (in hundredths of a second)

MAX_TEMPSEG_SIZE

NUMBER

Maximum temporary segment size (in bytes) created by an instantiation of this work area. This column is null if this work area has never spilled to disk.

LAST_TEMPSEG_SIZE

NUMBER

Temporary segment size (in bytes) created in the last instantiation of this work area. This column is null if the last instantiation of this work area did not spill to disk.